The role of multidrug resistance-1 (MDRI) variants in response to fexofenadine among Jordanians

Objective: The MDR1 gene encodes for P-glycoprotein (P-gp), which is an efflux transporter at the cell membrane. The P-gp has wide substrate specificity for multiple medications, including the anti-allergic drug fexofenadine. In this study, we investigated the possible association between three common MDR1 gene polymorphisms (G2677T, C3435T, and C1236T), and the anti-allergic effect of fexofenadine among Jordanians. Materials and methods: An assessment of the severity of allergic rhinitis symptoms was performed for all patients (n = 260) pre- and 7 days into fexofenadine. MDR1 polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: Relative to baseline, fexofenadine treatment was associated with significant reduction in allergic individual and total scores (p < 0.0001). Male gender was associated with less mean reduction in total allergic rhinitis symptoms score than in female (p < 0.05). In multivariate analysis, male gender was negatively correlated with response to fexofenadine (p = 0.01). The MDR1 gene C1236T polymorphism showed significant correlation with changes in total symptoms score from baseline in males (p < 0.05) but not in females. No significant correlation between fexofenadine response parameters and G2677T or the C3435T polymorphism was observed. Conclusions: The MDR1 gene polymorphism C1236T was associated with the anti-allergic effect of fexofenadine among male Jordanians.